Richards M W, Zeiaei S, Bagby M D, Okubo S, Soltani J
Department of Restorative Dentistry, West Virginia University, Morgantown 26506-9495, USA.
J Prosthodont. 1998 Dec;7(4):250-5. doi: 10.1111/j.1532-849x.1998.tb00213.x.
Using the one-step polyvinyl siloxane impression technique, this study compared the effect of putty material working time on the dimensional accuracy of recovered improved stone casts.
An acrylic resin master cast was fabricated with embedded reference points to enable both horizontal and vertical measurements. Four commercially available polyvinyl siloxane impression putties with light body washes were evaluated: 1) Extrude (Kerr), 2) Cutter (Coltere), 3) Express (3M), and 4) Reprosil (Caulk). Each putty was mixed by hand for 30 seconds, placed in a plastic stock tray, and seated on the master cast at 0, 30, 60, 90, and 120 seconds after mixing (N = 100, n = 5). The impressions were poured in improved stone, and vertical and horizontal measurements were made to 0.001 mm between reference points on recovered casts using an optical traveling microscope. ANOVA (p < or = .05) was used to compare vertical and horizontal measurements to master cast dimensions.
No statistically significant difference was found among casts for all materials and time periods tested. When horizontal measurement ranges were evaluated, Extrude casts exhibited the widest range of measurement, especially when the trays were seated at 90 and 120 seconds. When vertical measurement ranges were evaluated, Express casts at 120 seconds exhibited the widest range.
A high range of variability in vertical and horizontal dimensions occurred at the later time periods, especially for Extrude and Express casts. As a result of rapid polymerization and poor flow properties of putty materials, the impression tray should be seated within 60 seconds after putty mixing to reduce dimensional variability of recovered casts.
本研究采用一步法聚乙烯基硅氧烷印模技术，比较了油泥材料操作时间对所回收改良石膏模型尺寸精度的影响。
制作一个带有嵌入式参考点的丙烯酸树脂母模，以便进行水平和垂直测量。评估了四种市售的带有轻质体冲洗剂的聚乙烯基硅氧烷印模油泥：1）Extrude（ Kerr公司），2）Cutter（Coltere公司），3）Express（3M公司），4）Reprosil（Caulk公司）。每种油泥手工混合30秒，放入塑料成品托盘，并在混合后0、30、60、90和120秒放置在母模上（N = 100，n = 5）。将印模灌注到改良石膏中，并使用光学移动显微镜在回收模型上的参考点之间进行垂直和水平测量，精度达到0.001毫米。使用方差分析（p≤0.05）将垂直和水平测量结果与母模尺寸进行比较。
在所有测试材料和时间段的模型之间未发现统计学上的显著差异。在评估水平测量范围时，Extrude模型的测量范围最宽，尤其是当托盘在90秒和120秒放置时。在评估垂直测量范围时，120秒时的Express模型测量范围最宽。
在后期时间段，垂直和水平尺寸出现了很大的变异性，尤其是Extrude和Express模型。由于油泥材料的快速聚合和流动性差，印模托盘应在油泥混合后60秒内放置，以减少回收模型的尺寸变异性。
